If you are using firefox, go to preferences->content->colors and un-check "allow pages to choose their own colors". Puff, the main menu disappears.
This is really annoying web design. Images should be IMAGES, (with the good old <img src...> method) not part of the freaking background.
I don't want to see the horrible white every webpage uses to display text. I don't like staring directly at a turned on light bulb. That's why I like to be able to control the display of websites I visit. But unfortunately, more and more companies are using tricks instead of plain good old standard text html to get the job done. Why in the hell is the menu part of the background image?
It makes me not visit gog much, because visiting means I have to turn off this great feature and stare at a white-light-gray background for a while.

IT isn't part of the background image - its part of the custom style for the menu; Turning off that option in FF disables the CSS display options for websites you view - CSS w/ JavaScript is a much more efficient and faster method for displaying information than plain HTML.
Edit: plus with CSS it is much easier to share formatting across multiple pages on a large site. Using the old method you had to do shoddy coding with SSI that increases server load and load times

If you don't like the default colors, switch the theme. The alternate theme uses a light background with black text.

carlosjuero: ok, you are right about it not being part of the background, but still, what's wrong with using TEXT? You know, "games, catalogue, etc." That decreases loading time and makes it look much better.
How is firefox supposed to know what's part of the background and what is an image?
check this image out:
http://www.gog.com/www/default/-img/menu_1.gif
What is that?
cogadh: no, what I want is a BLACK background with light text. The alternate theme is even worse. And even if that was an option, it still would make me have to turn it off every time I visit, which means I can't visit other websites (like google) at the same time.

I disagree, the current CSS theme looks much better than plain text ever could, plus it is a design that is well within current accepted standards. Not to mention the vast majority of the site's visitors are not going to do what you did, so why alter the design just to suit a very small minority?

Well... Because this ranting is comparable to me ranting about stores using new currency? :D

heh... well, I hope it's a bit more valid than that. It's more like someone complaining their browser isn't supported by a website. Or someone complaining about a website that uses flash for everything. Yeah, so the majority can play flash. But, well, it sucks...

The website is nice. It's well-designed.
I think the buck stops there.

no website is going to work flawlessly if you are trying to mess with it on your end
it's already hard enough for webmasters to create websites that are compatible with all the different browsers, os', and resolutions out there, a website like gog that is attractive and functional is something to be thankful for

Okay, so that's not the point. This website could be the prettiest website in all the internet and my argument would still be valid. I choose usability over prettiness. I'm sure I'm not the only one.
Now, there are two arguments you guys are making here. One is valid and one, I'm claiming, isn't.
One is that the website is actually better the way it is now. If you believe that, that's ok. I don't. The prettiness isn't the point here, the usability is. Saying all the other websites are doing it just isn't true. There are only a few websites I visit regularly that have this problem. Google doesn't. Slashdot doesn't.
The other argument is that "why change if only a minority would use it anyway?". I'm saying that argument isn't valid.
*Sigh* I just thought of the perfect comparison. It's like back in the day of 800x600. I had a 1600x1200 resolution, and most websites couldn't be read at those resolutions, the font was too small. Specially when flash became popular. Back then I complained and got the same answers I'm getting here. "Why change if the majority of users are using 800x600?" they said.

Not to put too fine a point on it, but...
"Hello, Toyota? I'd like to complain about this car I just bought from you. I want the windshield wipers to go on automatically when I switch to the third gear, and I can't make them do that. I think I should be able to control how my car works."

Actually, no, I don't think users should really be able to control how sites are displayed (within reason, obviously some customization, such as font sizes, should always be at the user's preference). The GOG guys went to a lot of effort and expense to create something here that was meant to be experienced in the way they created it, not how you feel it should have been created. I would compare it to someone looking at the Mona Lisa and saying "Hey, I prefer blondes, so let me just slap a little yellow paint on her head... there, that's much better". Okay, so comparing a website to a classic work of art may be a bit extreme, but you get the idea.
I'm sorry, but as an avid Linux user, I am afraid you are very wrong about why everyone uses Windows. Yes, most popular apps are not designed for Linux (or other alternate OSes) because the vast majority of users are on Windows, but they are not on Windows because they apps are there, they are on Windows simply because that is what was already on their computer when they bought it. If, 15 years ago, pre-built machines had started shipping with a different OS, or if people were offered a choice of OS from the start, Windows might not be as ubiquitous as it is today, but the fact of the matter is, that never happened, Windows is everywhere and common business sense dictates that you don't waste resources on a product that will only appeal to a small number of people, you dedicate your resources to the product that will produce the most potential sales. In the case of software, that means you make it for Windows users. In the case of websites, that means you design it to suit the majority of users, not that rare person like yourself that disables functionality in their browser for the sake of personal aesthetics.

i always thought it was the other way.
EDIT: oh well, cogadh explained it better anyways.

So you don't think users should have any say on how any website displays in their own monitors? I disagree, I think everyone should be able to control how sites look like to them, and not each site control how itself looks like
If this is such an issue for you, why don't you just create your own style sheet to use for this site? You sound intelligent enough to research all the information and plugins you'd need to do as such.